The overall goal of this project is to increase the contributions of ultrasound to breast cancer detection and management by effecting extensive changes in the way ultrasound imaging can be employed. Current developments in 3D ultrasound registration and display of serial studies will be extended to make interpretation of repeat scans for detection of changes much more practical and effective. This will build on our current work with acquisition, display and quantification of 3D color Doppler imaging (CDI) and high resolution gray scale imaging. These efforts to enhance assessment of subtle changes within 3D volume will be directed toward prediction of response to neoadjuvant chemotherapy and toward detection and discrimination of small, malignant changes in the breast. These clinically relevant applications will also contribute toward the long term goal of developing improved methods for detection of occult breast cancer in high risk groups. Problems with ultrasound volume measurements of breast cancers include lesions that are too large or ill-defined. Proposed here are new approaches to image volume registration to allow ultrasound volume change measurements in essentially all cases, and to increase certainty that in a serial study, vascularity is measured in corresponding tissues. Compound ultrasound imaging consists of combining image volumes obtained from various look directions. This major change in ultrasound image volume formation promises increased contrast compared to speckle noise and more complete delineation of tissue layers and blood flowing normal to the main beam direction, usually with a small loss of resolution. The compound technique should eventually contribute to detection and quantification of breast lesions in single as well as serial studies. Significant problems to be addressed include suppression of registration errors caused by ultrasound attenuation shadows. In vivo evaluation of the compound image quality will be performed on cancers in the cohort of patients being studied with more conventional 3D imaging for detection and quantification of change.